Mn-Mg disordering in cummingtonite: a high-temperature neutron powder diffraction study

2000 ◽  
Vol 64 (2) ◽  
pp. 255-266 ◽  
Author(s):  
J. J. Reece ◽  
S. A. T. Redfern ◽  
M. D. Welch ◽  
C. M. B. Henderson
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
New York ◽  
High Temperature ◽  
Powder Diffraction ◽  
Elevated Temperatures ◽  
Neutron Powder Diffraction ◽  
Site Preference ◽  
A Site

AbstractThe crystal structure of a manganoan cummingtonite, composition [M4](Na0.13Ca0.41Mg0.46Mn1.00) [M1,2,3](Mg4.87Mn0.13)(Si8O22)(OH)2, (Z = 2), a = 9.5539(2) Å, b = 18.0293(3) Å, c = 5.2999(1) Å, β = 102.614(2)° from Talcville, New York, has been refined at high temperature using in situ neutron powder diffraction. The P21/m to C2/m phase transition, observed as spontaneous strains +ε1 = −ε2, occurs at ˜107°C. Long-range disordering between Mg2+ and Mn2+ on the M(4) and M(2) sites occurs above 550°C. Mn2+ occupies the M(4) and M(2) sites preferring M(4) with a site-preference energy of 24.6±1.5 kJ mol−1. Disordering induces an increase in XMnM2 and decrease in XMnM4 at elevated temperatures. Upon cooling, the ordered states of cation occupancy are ‘frozen in’ and strains in lattice parameters are maintained, suggesting that re-equilibration during cooling has not taken place.

High-temperature X-ray powder diffraction study of the tetragonal-cubic phase transition in nanocrystalline, compositionally homogeneous ZrO2–CeO2 solid solutions

2008 ◽  
Vol 23 (S1) ◽  
pp. S70-S74 ◽  
Author(s):  
L. M. Acuña ◽  
R. O. Fuentes ◽  
D. G. Lamas ◽  
I. O. Fábregas ◽  
N. E. Walsöe de Reca ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
Powder Diffraction ◽  
Solid Solutions ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray ◽  
First Order

Crystal structure of compositionally homogeneous, nanocrystalline ZrO2–CeO2 solutions was investigated by X-ray powder diffraction as a function of temperature for compositions between 50 and 65 mol % CeO2. ZrO2-50 and 60 mol % CeO2 solid solutions, which exhibit the t′-form of the tetragonal phase at room temperature, transform into the cubic phase in two steps: t′-to-t″ followed by t″-to-cubic. But the ZrO2-65 mol % CeO2, which exhibits the t″-form, transforms directly to the cubic phase. The results suggest that t′-to-t″ transition is of first order, but t″-to-cubic seems to be of second order.

High-temperature structural evolution of hexagonal multiferroic YMnO3and YbMnO3

2007 ◽  
Vol 40 (4) ◽  
pp. 730-734 ◽  
Author(s):  
Il-Kyoung Jeong ◽  
N. Hur ◽  
Th. Proffen
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Powder Diffraction ◽  
Structural Parameters ◽  
Structural Evolution ◽  
Neutron Powder Diffraction ◽  
Temperature Behaviour ◽  
Rietveld Refinements ◽  
Polar Structure ◽  
Diffraction Patterns

Neutron powder diffraction studies on the structural evolution of hexagonal multiferroic YMnO3and YbMnO3from 1000 K to 1400 K, and from 1000 K to 1350 K, respectively, are presented. The temperature evolution of diffraction patterns suggests that YMnO3undergoes a phase transition to a non-polar structure above 1200 K, while YbMnO3remains ferroelectric up to 1350 K. Detailed structural parameters were obtained as a function of temperature from Rietveld refinements. Based on this result, the distinct differences in temperature behaviour between YMnO3and YbMnO3, and the origin of the ferroelectricity in these hexagonal multiferroics are discussed.

scholarly journals The High-Temperature Transformation from 1T- to 3R-LixTiS2 (x = 0.7, 0.9) as Observed in situ with Neutron Powder Diffraction

2015 ◽  
Vol 229 (9) ◽  
Author(s):  
Dennis Wiedemann ◽  
Suliman Nakhal ◽  
Anatoliy Senyshyn ◽  
Thomas Bredow ◽  
Martin Lerch
Keyword(s):  
High Temperature ◽  
Powder Diffraction ◽  
Electrode Material ◽  
Room Temperature ◽  
Lithium Ion ◽  
Neutron Powder Diffraction ◽  
Titanium Disulfide ◽  
Temperature Transformation

AbstractLayered titanium disulfide is used as lithium-ion intercalating electrode material in batteries. The room-temperature stable trigonal 1T polymorphs of the intercalates Li

In situ high-temperature X-ray and neutron powder diffraction study of cation partitioning in synthetic Mg(Fe0.5Al0.5)2O4 spinel

2010 ◽  
Vol 38 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Nicoletta Marinoni ◽  
Davide Levy ◽  
Monica Dapiaggi ◽  
Alessandro Pavese ◽  
Ronald I. Smith
Keyword(s):  
High Temperature ◽  
Diffraction Study ◽  
Powder Diffraction ◽  
Neutron Powder Diffraction ◽  
X Ray
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